In many fluid production or injection well installations, fluid communication between the well and the earth formation penetrated by the well is carried out through perforations or other openings in a well casing or liner. In some instances, a well casing or liner may become split or otherwise damaged to place the well in fluid flow communication with the earth formation in an area where such communication is not desired. Other well conduits or production fluid tubing, for example, may also suffer unwanted damage which can cause fluid leakage.
Closing off casing perforations or sealing a fractured or otherwise damaged casing can be time consuming and expensive, particularly for wells in which other structural members such as production tubing strings and the like have been installed. The presence of a fluid production tubing string, for example, prevents the deployment of a sleeve or liner that is larger in diameter than the tubing string without first removing the tubing string from the well. In this regard, certain methods and apparatus have been contemplated for installing a sleeve in a well to at least substantially seal casing perforations without removing smaller diameter structures such as tubing strings from the well. Although the apparatus and methods described in the above-referenced patent application, for example, provide one means for effectively blocking well perforations there are certain well installations wherein differential pressures may exist between the formation and the wellbore which require a tighter seal than may be provided by an elastically expandable sleeve.
Another problem associated with conventional casing or tubing patching techniques is that conventional patching requires the use of spaced apart packers and a bridging section of tubing or casing to block the fracture or other source of unwanted leakage. This structure substantially reduces the useful diameter of the wellbore through which fluid is required to flow and through which various types of wellbore tools are desired to be inserted. Accordingly, a desirable casing or other well conduit patching device should reduce the inside diameter of the patched casing or conduit as little as possible.
It is to these ends that the present invention has been developed with a view to providing effective means and methods for sealing well casing perforations and other openings in casings or well conduits which are desired to be blocked to prevent fluid flow between a wellbore and an adjoining earth formation interval, or to prevent other unwanted flow to or from a well conduit.